In recent times, ultra-thin films of hafnium oxide (HfO2) have shown ferroelectricity (FE) attributed to the orthorhombic (o) phase of HfO2 with space group Pca21. This polar o-phase could be stabilized in the doped thin film of the oxide. In the present work, both polar and non-polar o-phases of HfO2 could be stabilized in Gd-doped bulk polycrystalline HfO2. Rietveld analysis of XRD data shows that the relative population of o-phases in the presence of the monoclinic (m) phase of HfO2 increases with increasing Gd-content. The local environment around the host atom has been investigated by time differential perturbed angular correlation (TDPAC) spectroscopy, synchrotron based X-ray near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) measurements showed a reduction in grain size with increasing Gd-dopant indicating a solute drag effect. It could be established that the segregation of the Gd-dopant in the grain boundary is a thermodynamically favorable process and the solute drag effect plays an important role in nucleation of the o-phase in bulk HfO2. Stabilization of Gd in both Pbca and Pca21 phases of HfO2 was supported by defect formation energy calculations using density functional theory (DFT). The present study has important implications in future applications of HfO2 in ferroelectric devices and in understanding the role of dopants in stabilizing the o-phase of HfO2 in the bulk.

Lymphatic filariasis (LF) is a chronic, neglected nematode parasite that infected filarial parasites. It is abundant in underprivileged communities across the globe. It is belonging to the group of rare neglected tropical diseases (NTD). After malaria, it is the leading infectious disease. Causative organisms Wuchereria bancrofti , Brugia malayi , and Brugia timori belong to the phylum Nematode. It affects billions of people in India and several other countries. They were asymptomatic, but now a day few symptoms have been observed such as lymphedema, elephantiasis and hydrocele. This disease shows close communication with humans by interacting with host immune systems. They disrupt monocytes/macrophages, dendritic cells, granulocytes, eosinophils, basophils, and Toll-like receptors. This review demonstrated macrophage cells’ (mɸs) role and their therapeutic approaches.

High-spin states of neutron-deficient trans-lead nucleus $$^{204}\hbox {At}$$ were populated up to $$\sim 8\,\mathrm{MeV}$$ excitation through the $$^{12}\hbox {C} + ^{197}\hbox {Au}$$ fusion evaporation reaction. Decay of the associated levels through prompt and delayed $$\gamma $$ -ray emissions were studied to evaluate the underlying nuclear structure. The level scheme, which was partly known, was extended further. An isomeric $$16^+$$ level with observed mean lifetime $$\tau =52 \pm 5\, \mathrm{ns}$$ , was established from our measurements. Attempts were made to interpret the excited states based on multi quasiparticle and hole structures involving $$2f_{5/2}$$ , $$1h_{9/2}$$ , and $$1i_{13/2}$$ shell model states, along with moderate core excitation. Magnetic dipole band structure over the spin parity range:  $$16^+$$ – $$23^+$$ was confirmed and evaluated in more detail, including the missing cross-over E2 transitions. Band-crossing along the shears band was observed and compared with the evidence of similar phenomena in the neighbouring $$^{202}\hbox {Bi}$$ , $$^{205}\hbox {Rn}$$ isotones and the $$^{203}\hbox {At}$$ isotope. Based on comparison of the measured B(M1)/B(E2) values for transitions along the band with the semiclassical model based estimates, the shears band of $$^{204}\hbox {At}$$ was established along with the level scheme.

Temperature dependent phase transformation behavior in cobalt from hexagonal close-packed (hcp) to face centered cubic (fcc) has been found to be contradictory to that reported earlier. It is found that hcp phase stabilizes at both low and high temperature ([Formula: see text]873 K) while fcc phase is stabilized at [Formula: see text]500 K. At 298 K, hcp Co has been found to be predominant ([Formula: see text]70%) where hcp magnetic phase is [Formula: see text]60%. At 973 K, hcp phase is again predominant ([Formula: see text]73%), but it is mainly the non-magnetic phase ([Formula: see text]67%). Contrary to present results, it was found earlier that fcc phase was stabilized at high temperature and hcp to fcc transformation occured at [Formula: see text]700 K. Present results from perturbed angular correlation measurements, therefore, requires a new theoretical interpretation for Co phase transformation. From present measurements, hyperfine magnetic fields in Co at room temperature for the hcp and fcc phases have been found to be 18.7(6) and 12.8(3) T, much lower than earlier reported results. The hyperfine magnetic fields at [Formula: see text]Ta impurity atom have been calculated by density functional theory (DFT) employing the full potential (linearized) augmented plane wave method (FP-LAPW). Present calculated results for both hcp and fcc phases corroborate our experimental results.

Temperature dependent phase transformation behavior in Co from hcp to fcc has been found to be contradictory to that reported earlier. It is found that hcp phase stabilizes at both low and high temperature (∼873 K)while fcc phase is stabilized at ∼500 K. At 298 K, hcp Co has been found to be predominant (∼70%) where hcp magnetic phase is ∼60%. At 973 K, hcp phase is again predominant (∼73%), but it is mainly the non-magnetic phase (∼67%). Contrary to present results, it was found earlier that fcc phase was stabilized at high temperature and hcp to fcc transformation occured at ∼700 K. Theoretical models show that non-magneticfcc phase is more stable than non-magnetic hcp phase and presence of magnetism destabilizes the fcc phaseat low temperature. Present results from perturbed angular correlation measurements, therefore, requires anew theoretical interpretation for Co phase transformation. From present measurements, hyperfine magneticfields in Co at room temperature for the hcp and fcc phases have been found to be 18.7(6) and 12.8(3) T, much lower than earlier reported results. The hyperfine magnetic fields at 181Ta impurity atom have been calculated by density functional theory (DFT) employing the full potential (linearized) augmented plane wave method (FP-LAPW). Present calculated results for both hcp and fcc phases corroborate our experimental results.

The low-lying states of 117,118Sn have been studied from the decay of 117g,118mSb, and 117mSn. These long-lived species were populated through the reaction 4He + natIn at Elab = 32 MeV. Singles, as well as γ-γ coincidence data, were acquired. The uncertainties in the placement of some of the γ-rays in the excitation spectra of 118Sn observed by previous workers have been removed. A γ-ray (984 keV) previously assigned to 118Sn has been eliminated from the level scheme, based on the present analysis. The decay half-lives of 117g,118mSb have been remeasured. The slope method and deconvolution technique have been used to determine the half-lives of a few isomeric states in 117,118Sn. The results are interpreted in the framework of large scale shell model calculations performed in the 50 - 82 valence shell using truncations. Although the excitation energies were not reproduced well, the theoretical calculations could reasonably reproduce the isomers' transition probabilities due to their nearly pure configuration.

The intermetallic alloy Zr9Pd11 has been studied by perturbed angular correlation (PAC) spectroscopy using Hf-181 probe to confirm its phase existences and to determine temperature stability of the compound. Another compound Zr13Pd12 which was reported to be present by a single group of authors and is yet to be verified by any other measurements has been studied by X-ray diffraction (XRD) to support or disprove its phase existence. Both the compounds have been synthesized by argon arc melting and for Zr9Pd11, results from atomic scale PAC measurements have been reported here for the first time. From present PAC measurement at room temperature, values of quadrupole frequency and asymmetry parameter corresponding to Zr9Pd11 have been found to be omega(Q) = 45.6(2) Mrad/s,eta = 0.84(1), respectively. The variation of eta with temperature has been found to be in opposite direction compared to that observed in ZrPd. From powder XRD pattern in Zr9Pd11, a predominant phase of Zr9Pd11 along with two other minor phases of Zr-Pd system (Zr3Pd4 and ZrPd3) have been observed in the sample. From XRD measurements in stoichiometric Zr13Pd12 sample, no phase of Zr13Pd12 has been observed. In this sample, the phase compositions are found to be monoclinic ZrPd (space group Cm), Zr9Pd11 (space group P4/m) and ZrPd austenite (space group Pm (3) over barm). Present results, therefore, do not support the previously reported phase existence of Zr13Pd12.

The recent observation of ferroelectricity in ultra thin films of hafnium oxide (HfO2) has been attributed to the orthorhombic (o) phase of HfO2 with space group Pca2(1). Although this oxide is polymorphic in nature, this polar o-phase is known to be stabilized in the doped thin film oxide. The objective of the present experiment is to stabilize the o-phases in La doped bulk polycrystalline HfO2 and investigate their evolution with the doping concentration through Time Differential Perturbed Angular Correlation (TDPAC), X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) measurements. The present work reports the presence of both the polar Pca2(1) phase and the antipolar Pbca phase at different La-concentrations. Two o-phases of HfO2 with space groups Pca2(1) and Pbca, difficult to distinguish by other complimentary methods, could be unambiguously identified by utilizing the atomic scale sensitivity of the electric field gradient (EFG) embedded in TDPAC spectroscopy. The determination of the oxidation state and the local environment of La-atoms by XANES and EXAFS measurements illuminates the microscopic role of the dopant in stabilizing the o-phase. The "solute drag model" proposes a critical crystallite size for the nucleation of the o-phase in bulk HfO2 and explains the role of the La-dopant in stabilizing the o-phase. Thus the present study shows the possibility of stabilizing the polar o-phase and hence attaining ferroelectricity in bulk HfO2 to augment the scope of future application for this ferroelectric device.

Ferromagnetism in Hf6Co23 intermetallic alloy at room temperature has been confirmed from perturbed angular correlation measurements using 181Hf probe. The strength of hyperfine magnetic field at room temperature for this intermetallic compound has been found to be Bhf = 2.5(2) T while the earlier report of hyperfine magnetic field in Hf6Co23 has discrepancy. The hyperfine magnetic field at Ta impurity site has also been calculated by density functional theory and the result is found to be Bhf = -4.964 T (at 0 K). This value is closer to the present experimental value measured at 298 K. The compound Hf6Co23 has been found to decompose reversibly to Hf2Co7 at 473 K. Ferromagnetism in this material has been found up to 423 K and its Curie temperature is, therefore, set as TC > 423 K. From recent measurements by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, electron probe microanalysis and differential scanning calorimetry, Hf6Co23 was reported to be stable in a wide range of temperature and there was no phase existence of Hf2Co7 while the previous reported phase diagram showed a decomposition of Hf6Co23 to Hf2Co7 at a higher temperature.

The equiatomic alloy HfPd has been studied by perturbed angular correlation (PAC) spectroscopy using Hf-181 probe to observe its phase transformation with temperature. At room temperature, the martensitic phase of HfPd ((similar to)57%), Hf2Pd ((similar to)19%) and HfPd2 ((similar to)24%) have been found. At a slightly higher temperature (373 K and above), no phase of HfPd2 is observed but, both martensitic and cubic austenite phases of HfPd are found. The phase Hf2Pd is present in the whole temperature range. Up to 573 K, the cubic austenite phase of HfPd is found to increase with temperature at the expense of martensitic HfPd phase. At 673 K, the phase Hf2Pd increases abruptly and remains same in the temperature range 673-973 K ((similar to)30%). The cubic HfPd phase remains almost unchanged in this temperature range ((similar to)38%). From present measurements, beginning of phase transformation from martensitic to austenite is found at a much lower temperature of 373 K. In the temperature range 373-973 K, both martensitic and austenite phases of HfPd coexist while from previous measurements by differential scanning calorimetry, the cubic austenite to martensitic phase transformation was found at about 823 K. XRD measurements at room temperature have also been carried out to identify the different phases of Hf-Pd. The new Hf2Pd3 phase of Hf-Pd system that was reported by a sole group has been confirmed from present powder XRD pattern in annealed sample.

Perturbed angular correlation (PAC) measurements in Hf2Co7 have been performed in the temperature range 77-973 K using the Hf-181 probe to observe ferromagnetism in this intermetallic alloy. From present measurements, no magnetic interaction is observed at any temperature in the above temperature range. Only two quadrupole interaction frequencies have been found. At room temperature, values of quadrupole frequency and asymmetry parameter are found to be omega(Q) = 15.7(4) Mrad/s, eta = 0, delta = 0 for site 1 (similar to 71%) and omega(Q) = 46(1) Mrad/s, eta = 0.74(5), delta = 5(3)% for site 2 (similar to 29%). Present results contradict with the earlier reported results where a room temperature ferromagnetism was found with a Curie temperature of similar to 400 K. X-ray diffraction measurement in Hf2Co7 has also been performed. From the measured XRD pattern, an almost pure phase of Hf2Co7 was observed.

In pure HfO2, only P21/c monoclinic phase was known to exist from previous investigations and there is no report of orthorhombic phase in pure bulk HfO2 at ambient temperature and pressure. Present atomic scale measurements by perturbed angular correlation (PAC) spectroscopy, report two orthorhombic phases in pure bulk HfO2 at room temperature along with the most commonly observed monoclinic phase (similar to 80%). By comparing with the calculated results of density functional theory using full potential (linearized) augmented plane wave method (FP-LAPW), these two orthorhombic phases have been attributed to structures with space group Pbca and Pca2(1). The structures with space group Pca2(1) and Pmn2(1) are non-centrosymmetric and were found to be responsible for ferroelectricity in doped thin film HfO2. At room temperature, the site percentages for the Pca2(1) and Pbca have been found to be similar to 6% and similar to 10%, respectively. At high temperatures of 973 and 1073 K, the Pca2(1) phase was not found but, the Pbca orthorhombic phase was found to be present in the whole temperature range from 298 to 1073 K. The third orthorhombic phase Pmn2(1) was not observed in bulk HfO2. Interestingly, In Gd doped (similar to 5 at%) HfO2, these two orthorhombic phases enhance more than the monoclinic phase. In Gd doped oxide, the P21/c monoclinic phase reduces to similar to 24% while the site percentages for the two orthorhombic phases have been found to be similar to 54% (Pbca) and similar to 17% (Pca2(1)).

High spin states of neutron deficient Trans-Lead nucleus $^{204}$At were populated up to $E_x \sim 8\,{\rm MeV}$ through the $^{12}$C + $^{197}$Au fusion evaporation reaction. Decay of the high spin states including prompt and delayed gamma ray emission were studied to understand the underlying nuclear structure. The level scheme, which was partly known from earlier studies, was extended further through our experiment and analysis of spin and parity of the associated levels. An isomeric $16^+$ level $(\tau=52(5)\, {\rm ns})$, corresponding to $M2$ transition, was established from our measurements. Attempts were made at interpretation of the excited states based on multi quasiparticle and hole structure involving $2f_{5/2}$, $1h_{9/2}$, and $1i_{13/2}$ shell model states, along with moderate core excitation. Magnetic dipole band structure over the spin parity range:~$16^+ - 23^+$, which was found in the earlier Gammasphere study, was confirmed and explored in more detail, including the missing cross-over $E2$ transitions. Band-crossing along the shears band was observed and compared with the evidence of similar phenomena in the neighboring neutron deficient $^{202}$Bi, $^{205}$Rn isotones and the neighbouring $^{203}$At isotope. Based on comparison of the measured $B(M1)/B(E2)$ values for transitions along the band with the semiclassical model based estimates, the shears band of $^{204}$At was firmly established along with the level scheme.

Due to technical constraints this article was published in volume 240:1 with erroneous article citation ID number 8 whereas this should have been 78 which is corrected as such. Springer Nature sincerely apologizes towards the author(s) for the inconvenience caused.

The equiatomic alloy ZrPd has been studied by perturbed angular correlation (PAC) spectroscopy in the temperature range 298-973 K to observe the martensitic to austenite phase transformation. In ZrPd, a predominant component (∼56%) found at room temperature with values of quadrupole frequency ωQ = 39.5(5) Mrad/s, asymmetry parameter η = 0.44(2) and frequency distribution width δ = 10(2)% is tentatively assigned to the monoclinic martensitic phase of ZrPd. At 373 K, a small component (∼7%) with values of ωQ = 26(3) Mrad/s, η = 0 appears which enhances with temperature at the expense of the martensitic phase and is found to be ∼35% at 973 K. This new component, probably, arises due to structural transition from monoclinic martensitic to cubic austenite phase, a phase transformation reported to occur around 830 K in previous work.

Crystalline phases formed in stoichiometric Zr9Ni11 and Hf9Ni11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr9Ni11, the phases Zr9Ni11 (-89%) and Zr8Ni21 (similar to 11%) have been found at room temperature from PAC measurements. At 773 K, Zr9Ni11 partially decomposes to Zr7Niio and at 973 K, it is completely decomposed to ZrNi and Zr7Niio. In Hf9Ni11, a predominant phase (similar to 81%) due to HfNi is found at room temperature while the phase Hf9Ni11 is produced as a minor phase (similar to 19%). No compositional phase change at higher temperature is found in Hf9Ni11. Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr9Ni11 and Hf9Ni11 have been calculated by density functional theory (DFT) using all electron full potential (linearized) augmented plane wave plus local orbitals [FP-(L)APW+lo] method in order to assign the phase components.

This article has been corrected because one of the authors given names was incorrect.

From temperature dependent perturbed angular correlation (PAC) measurements (77–873 K) in equiatomic TiNi intermetallic alloy, martensitic phase transformations have been observed. Three frequency components corresponding to three different phases of TiNi have been found in the temperature range 298–873 K. The results of quadrupole frequency and asymmetry parameters at room temperature are found to be: ω Q = 14(1) Mrad/s, η = 0 (33%), ω Q = 40.0(5) Mrad/s, η = 0.66(3) (52%) and ω Q = 56.7(3)Mrad/s, η = 0.39(2) (15%). The frequency component with η = 0 and which enhances to ~52% at 373 K can be attributed to the cubic austenite phase. The predominant component (~52%) found at room temperature has been attributed to monoclinic martensitic phase of TiNi and the third component with values of ω Q and η similar to those for the martensitic phase is attributed to the intermediate orthorhombic phase. At 77 K, no intermediate and austenite phases have been found but only the martensite phase is observed at this temperature. From XRD measurements at room temperature also, three phases of TiNi have been observed.