Materials Literature
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Ammonium iodate, NH4IO3, is pyroelectric at room temperature and crystallizes in the orthorhombic system with space group Pc21n and four formulas in the unit cell. The lattice constants at 297°K are a = 6.4115 ± 0.0005, b = 9.1706 ± 0.0005, and c = 6.3740 ± 0.0005 Å. The integrated intensities of 4591 reflections with…
MnAlGe is a uniaxial ferromagnetic compound with a saturation 4πMs of 3600 G, and Curie temperature of 245°C. We have studied polycrystalline thin films of this compound formed on various substrates by getter sputtering. The optimum substrate temperature to obtain films with uniform magnetic properties was 500°C. Film…
The application of Mori's theory of fluctuations to the calculation of depolarized light scattering spectra of liquids is described. Two sets of kinetic equations are derived. The first is capable of describing the shear wave doublet observed by Fabelinskii and co-workers and Stegeman and Stoicheff and reduces to the…
The room-temperature ac conductivity and the real part of the dielectric constant of amorphous Se, ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$, and ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ have been measured in the 1.0 \ifmmode\times\else\texttimes\fi{} ${10}^{2}$ - 3.6 \ifmmode\times\else\texttimes\fi{} ${10}^{10}$-Hz freque…
In strongly Van Vleck paramagnetic rare-earth alloys or compounds, large hyperfine fields can be induced at the rare-earth nucleus with moderate external fields. These fields are useful to generate low temperatures by the method of nuclear adiabatic demagnetization. Experiments in the Van Vleck paramagnets PrPt5 and P…
C-15 type structure V2HfxZr1−x shows a high resistive critical field exceeding 200 kOe at 4.2°K whenever x>0.3. The highest transition temperature, 10.1°K, and critical field, 230 kOe, are achieved with the composition V2Hf0.5Zr0.5. For this material the critical current density at 4.2°K and 130 kOe is as high…
New single-phase alloys have been prepared having the compositions T2MnX and TMnX, where T represents the platinum-group or palladium-group metal, and X is an element of groups III, IV, or V. Their crystal structures are ordered forms of the bcc structure. Some are apparently ferromagnetic with Curie temperatures of s…
The behavior of the resistance of polycrystalline aluminum wires as a function of magnetic field and purity at temperatures of 4, 15, and 19.6 K is reported. Both longitudinal and transverse configurations were measured. The residual resistance ratios of the specimens varied from 1600 to 31 000. The measured magnetore…
Copper metaborate crystallizes in the tetragonal system, space group l~2d, with twelve formula units in a cell of dimensions a = 11.484 4-_ 0.004 and c = 5.620 _+_ 0.004/~,. The calculated density is 4.02 g.cm -3. The structure of CuB204 has been determined by three-dimensional Fourier syntheses. The positional and is…
Mössbauer spectroscopy has been used to study the magnetic properties of ferric oxychloride FeOCl. A paramagnetic to antiferromagnetic transition occurs at 92°±3°K. Near liquid-helium temperature the antiferromagnetic structure is noncolinear; at least two sets of nonequivalent Fe3+ sites and a doubling of the unit ce…
Zinc diborate crystallizes in the orth0rhombic system, space group Pbca, with eight formula units in a cell of dimensions a= 13"714_+0"005, b=8"091 _+0.005 and c=8.631 _+0.005 A. The calculated density is 3"07 g.cm-3, and all atoms are in general positions. The structure of ZnB407 has been solved by three-dimensional…
Mn3O4 is a tetragonal spinel I41/amd. It is ferromagnetic below Tc = 43°K. At 4.2°K neutron diffraction measurements on powdered samples show the presence of 8 sublattices in a unit cell a, 2a, c which is double the chemical unit cell. These 8 sublattices are arranged as follows: 2 sublattices at tetrahedral sites and…
Application of a sufficiently strong magnetic field Hx along the antiferromagnetic easy axis (x) of the isomorphic, distorted perovskites YFeO3 and YCrO3, results in the smooth rotation of the antiferromagnetic vector in the x-z plane, reaching the z axis at the critical fields Hcr=74±1 kOe and Hcr=40±1 kOe at 4.2°K,…
In Sm2+X compounds (X = S, Se, Te) an unusualy large dependence of the low-temperature Van Vleck susceptibility on the ligand has been observed. SmSe, SmTe, and also TmTe undergo a continuous insulator-metal transition under pressure. In contrast, SmS shows a discontinuous transition to the metal at 6.5 kbar. In all c…
The high-temperature heat contents of high-purity YF3, LaF3, PrF3, NdF3, GdF3, HoF3, and LuF3 were measured from 100–1600°C. The heat capacity, heats of transition, heats of fusion, and related thermodynamic functions were calculated. The smoothed values of H°T − H°298, Cp, S°T − S°298, and − (F°T − H°298) / T are tab…
Ferroelectric K(6−x−y)Li(4+x)Nb(10+y)O30, with x ≃ 0.07, y ≃ 0.23, and a Curie temperature of 613°K, crystallizes with a tungsten bronze-type structure in the tetragonal system. The lattice constants are a = 12.5764 ± 0.0002 and c = 4.0149 ± 0.0001 Å at 298°K. The space group is P4bm. There is one formula per unit cel…
Excitation of electrons between parallel or near-parallel one-electron bands in simple polyvalent metals constitutes a major source of the observed optical absorption. Much of the effect can be accounted for in a straightforward calculation of both real and imaginary parts of the conductivity, which does not require t…
Raman scattering has been studied in the amorphous form of Si and several related, tetrahedrally bonded semiconductors (Ge, GaAs, GaP, InSb). All vibrational modes of the material can take part in the scattering process, and the Raman spectrum is a measure of the density of vibrational states. The amorphous phases are…
Rapid crystallization and equally rapid revitrification of amorphous chalcogenide films exposed to short laser pulses has been observed. A model is developed in which both the speed of crystallization and the reversibility are attributed to the large enhancement of crystallization rate under the influence of the photo…
Abstract The saturation magnetizations of very pure iron and nickel have been measured absolutely by a force method at room temperature. The values are 217.6 and 55.1 emu/g (217.6 and 55.1 J T-1 kg-1) respectively. The theory and reliability of the force method are investigated and discussed. New measurements have als…