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A new high pressure phase of MN TiO3 and its magnetic property
iv 12.
ABSTRACTS OF PAPERS TO APPEAR IN 3. PHYS. CHEM. SOLIDS IONIC CONDUCTION IN PURE AND DOPED SINGLE-CRYSTALLINE LITHIUM IODIDE B.J.H. Jackson and D.A. Young (Department of Chemical Engineering and Chemical Technology, Imperial College, London, S.W.7)
The free energy of defect formation and the activation ener~rfor motion of the most mobile defect have been determined from the ionic conductivity of As-grown and Mg-doped single crystals of lithium iodide. Values obtained are Sj = 4.5k, h, 1.06eV with hm(cation vacancy) 0.43 eV, giving a defect concentration at the melting point X0(Tm) = 0.18 at.%, concordant
The system of partial differential equations which describes the motion of charge carriers inside the space charge region of an inversely biased p—n junction is numerically solved, taking into account the Influence of the density of electron-hole pairs on the electric field. It is shown that there are remarkable variations in the theoretically predicted current signals when the density is raised. Particularly interesting Is the appearance of a peak closely resembling the one predicted by the theory of SCL currents in insulators. The time position of the above mentioned peak is not influenced by diffusion (at least when a realistic order of magnitude is considered for the diffusion term).
with the other alkali halides. (Received 8 November 1968)
13.
PREPARATION AND PROPERTIES OF SINGLE CRYSTAL CuA1S2 AND CuAlSe2 W.N. Honeyman (Department of Applied Physics, Brighton College of Technology, Brighton, Sussex)
Single crystals of the I—III—V12 ternary semiconductors CuA1S2 and CuA1Se2 have been prepared by vapour transport with iodine. Optical transmission measurements give energy gaps of about 3.35eV (sulphide) and 2.5eV (selenide). Double refraction is observed, and the refractive indices extrapolated to infinite wavelength are 2.300 and 2.325 (sulphide) and 2.437 (selenide). The selenide shows large photoconductive effects, while both semiconductors have electrical resistivities from iO~to 2 V~’ s’. iO~Cl cm and mobilities less than 6001fl (Received 12 September 1968) (Revised 24 January 1969)
14.
SPACE CHARGE LIMITED CURRENTS IN PN JUNCTIONS A. Taroni (University of Modena), and G. Zanarini (University of Bologna)
Vol. 7, No. 6
These theoretical previsions could be very useful in theat study of charge transport in semiconductors low fields. (Received 18 November 1968) 15.
A NEW HIGH PRESSURE PHASE OF MnTiO3 AND ITS MAGNETIC PROPERTY Yasuhiko Syono, Syun-iti Akimoto Yoshikazu Ishikawa and Yasuo Endoh (The Institute for Solid State Physics, The University of Tokyo, Roppongi, Minato-ku, Tokyo, Japan)
A high pressure phase of MnTiO3 II is newly synthesized at high pressures and temperatures. An equilibrium phase boundary between an atmospheric pressure phase of MnTiO3 I and MnTiO3 II is p(kb) = 110— 0.044T(°C). X-ray analysis of powder specimens has revealed that the high pressure phase MnTiO3 II has the disordered ilmeniteofstructure with the lattice parameters a — 5.2051A, c —hexagonal 13.699A, c/a = 2.632 and V = 321.4A3. The transformation from MnT1O 3 I to MnTiO3 II causes an expansion of the a axis by 1.3% and a contraction of the c axis by 4.1%, resulting a volume decrease of 1.6%. Both Mössbauer effect and paramagnetic ESR measurements suggest that MnTiO ~II is antiferromagnetic below 24°±1°K. The magnetic susceptibility obeys the Curie—Weiss law almost doWn to the Ned
Vol. 7, No. 6
ABSTRACTS OF PAPERS TO APPEAR iN
temperature and slightly deviates from it below TN, in marked contrast with that of MnTiO3 I. 2’ ions A possibility that the of magnetic Mn plays an important rolecovalency both in the interactions and the crystal stability of manganese ilmenites is suggested. (Received 12 November 1968) (Revised 24 January 1969)
3.
PHYS. CHEM. SOLIDS
v
ABSTRACTS OF PAPERS TO APPEAR IN 3. PHYS. CHEM. SOLIDS IONIC CONDUCTION IN PURE AND DOPED SINGLE-CRYSTALLINE LITHIUM IODIDE B.J.H. Jackson and D.A. Young (Department of Chemical Engineering and Chemical Technology, Imperial College, London, S.W.7)
The free energy of defect formation and the activation ener~rfor motion of the most mobile defect have been determined from the ionic conductivity of As-grown and Mg-doped single crystals of lithium iodide. Values obtained are Sj = 4.5k, h, 1.06eV with hm(cation vacancy) 0.43 eV, giving a defect concentration at the melting point X0(Tm) = 0.18 at.%, concordant
The system of partial differential equations which describes the motion of charge carriers inside the space charge region of an inversely biased p—n junction is numerically solved, taking into account the Influence of the density of electron-hole pairs on the electric field. It is shown that there are remarkable variations in the theoretically predicted current signals when the density is raised. Particularly interesting Is the appearance of a peak closely resembling the one predicted by the theory of SCL currents in insulators. The time position of the above mentioned peak is not influenced by diffusion (at least when a realistic order of magnitude is considered for the diffusion term).
with the other alkali halides. (Received 8 November 1968)
13.
PREPARATION AND PROPERTIES OF SINGLE CRYSTAL CuA1S2 AND CuAlSe2 W.N. Honeyman (Department of Applied Physics, Brighton College of Technology, Brighton, Sussex)
Single crystals of the I—III—V12 ternary semiconductors CuA1S2 and CuA1Se2 have been prepared by vapour transport with iodine. Optical transmission measurements give energy gaps of about 3.35eV (sulphide) and 2.5eV (selenide). Double refraction is observed, and the refractive indices extrapolated to infinite wavelength are 2.300 and 2.325 (sulphide) and 2.437 (selenide). The selenide shows large photoconductive effects, while both semiconductors have electrical resistivities from iO~to 2 V~’ s’. iO~Cl cm and mobilities less than 6001fl (Received 12 September 1968) (Revised 24 January 1969)
14.
SPACE CHARGE LIMITED CURRENTS IN PN JUNCTIONS A. Taroni (University of Modena), and G. Zanarini (University of Bologna)
Vol. 7, No. 6
These theoretical previsions could be very useful in theat study of charge transport in semiconductors low fields. (Received 18 November 1968) 15.
A NEW HIGH PRESSURE PHASE OF MnTiO3 AND ITS MAGNETIC PROPERTY Yasuhiko Syono, Syun-iti Akimoto Yoshikazu Ishikawa and Yasuo Endoh (The Institute for Solid State Physics, The University of Tokyo, Roppongi, Minato-ku, Tokyo, Japan)
A high pressure phase of MnTiO3 II is newly synthesized at high pressures and temperatures. An equilibrium phase boundary between an atmospheric pressure phase of MnTiO3 I and MnTiO3 II is p(kb) = 110— 0.044T(°C). X-ray analysis of powder specimens has revealed that the high pressure phase MnTiO3 II has the disordered ilmeniteofstructure with the lattice parameters a — 5.2051A, c —hexagonal 13.699A, c/a = 2.632 and V = 321.4A3. The transformation from MnT1O 3 I to MnTiO3 II causes an expansion of the a axis by 1.3% and a contraction of the c axis by 4.1%, resulting a volume decrease of 1.6%. Both Mössbauer effect and paramagnetic ESR measurements suggest that MnTiO ~II is antiferromagnetic below 24°±1°K. The magnetic susceptibility obeys the Curie—Weiss law almost doWn to the Ned
Vol. 7, No. 6
ABSTRACTS OF PAPERS TO APPEAR iN
temperature and slightly deviates from it below TN, in marked contrast with that of MnTiO3 I. 2’ ions A possibility that the of magnetic Mn plays an important rolecovalency both in the interactions and the crystal stability of manganese ilmenites is suggested. (Received 12 November 1968) (Revised 24 January 1969)
3.
PHYS. CHEM. SOLIDS
v