BYAs p a r t of a systematic study on lattice dynamics of hexagonal metals /l/ this note reports on anisotropic atomic vibrations and the thermal expansion coefficient in titanium. Titanium is a polymorphous metal, below 1155 K it has a closepacked hexagonal structure and crystallizes into the magnesium-type lattice with an axial ratio of 1.587, i.e. the crystal is compressed along the c-axis. istics /2, 3/ and on the anisotropy of the thermal expansion coefficient /4 to 6/.
Synthesis and Dielectrical Properties of Ternary SolutionsPbScx/2Al(1-x)/2Nb1/2O3 with Metastable Perovskite-Type Structure.-The metastable perovskite-type title compound is prepared from the element oxides at high pressure (5.5-6.0 MPa) and temp. (1500-1700 . degree.C). The ceramic is a ferroelectric with a smeared phase transition into a paraelectric phase. -(OLEKHNOVICH, N. M.; ZHABKO, T. E.; SALAK, A. N.; PASHKOVSKII, O. I.; SHILIN, A. D.; UNYARKHA, O. V.; Neorg. Mater. 30 (1994) 7, 976-979; Inst. fiz. tverd. tela poluprovodn. Akad. nauk Belarusi, Minsk, Belarus; RU)
The X-ray studies of the tetragonal YRa,Cu,07-, compound are performed at different temperatures from 400 t o 90 K and the temperature variation of the thermal expansion coefficients and the Debye characteristic temperature is determined. The anisotropy of thermal expansion is investigated. It is found that the two dynamical characteristics monotonously decrease with temperature lowering whereas for the superconducting orthorhombic modification their temperature dependences are anomalous. The mean thermal expansion coefficient as well as the overall Debye temperature for the tetragonal phase are smaller than those for the orthorhombic one. HpOBeneHbI peHTreHOrpa@IIYeCKPie IICCJIeAOBaHIIR TeTparOHanbHOfi MOnH@HKaqIIII COe-HbIe 3aBMCHMOCTH K03@@IIUHeHTOB TenjIOBOrO paClIlHpeHllR II lge6aeBCKOfi XapaKTepIICTEi-YCTaHOBJleHO, YTO 06e AIIHaMII~IeCK&fe XapaKTepIICTHKH MOHOTOHHO YMeHbUalOTCfi C llOHIIWeHIIe7vl TeMIIepaTypbI, B TO BpeMR KaK &lTf3 pOM6HYeCKOii MOnH@IIKaUHH TeMnepa-TYpHbIe 3aBIICIIMOCTII 3THX XapaHTepIICTHK HOCElT aHOMajIbHbIfi XapaKTep. CpenHHe TeTpaI' OHaJIbHOfi MOAH@PiKaqHII MeHbLLIe , YeM HJIFI pOM6HYeCIcO8. ,wHeHm YBa,Cu,07-Z B mmepsane TeMnepaTyp 400-90 H II onpeaeneHbI TeMnepaTyp-YecKofi TeMnepaTypbI. HccjIefiosaH xapamep ~H H~O T P O~M H TennoBoro pacmmpeHmn. 3 1 r a q e~~~ H O~@ @ I I I J M~H T~ TenjIoBoro pacruPipeHm H ~e 6 a e s c~o i i TeMnepaTypbi nn~l
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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