Magnetic susceptibility semiconductors

With respect to the physical properties mentioned, band-structure calculations have attracted considerable interest, e.g., for SbSBr, SbSI, and SbSel (234). For the compounds having reference 22i in column 4 of Table XXIX, a temperature-independent diamagnetism has been found, with values of about 10 cm" g between 77 and 340 K. A small temperature-dependence is exhibited by BiTel, a narrow-gap semiconductor (41). The anisotropy of the magnetic susceptibility has been studied for SbSI, BiSel, and BiTel (41, 420). 

It would seem that the carrier identification would be readily resolved by experiment. In fact, numerous experiments have found the carriers to be electrons in BaPb B Og (78)(79), the carrier concentration and Tc readily scaling with Bi content until a CDW decreases the carrier density. This interpretation is well supported by a magnetic susceptibility study (80). Even though the parent compound BaBiOg is a hole type semiconductor (81), the carrier type has been shown to be n or electronic in character (75) in Ba K BiOg. 

In all of this work there was little suggestion that the surface states of the palladium might behave differently from bulk states. Selwood (17) indicated that, from some sorption-magnetic susceptibility data for hydrogen sorbed on palladium which was finely dispersed on alumina gel, the ultimate sorption capacity was approximately at the ratio 2H/Pd. Trzebiatowsky and coworkers (25) deposited palladium on alumina gel in amounts ranging from 0.46 to 9.1% of gel weight. They found the palladium to be present in a normal crystal lattice structure, but its susceptibility was less than for the bulk metal. This suggested to the present authors that the first layer of palladium atoms laid down on the alumina gel underwent an interaction with the alumina, which has some of the properties of a semiconductor. Such behavior was definitely shown in this laboratory (22) in the studies on the sorption of NO by alumina gel. Much of this... 

In this salt (MDT = l-methyl-l,4-dithianium), there is a brick wall stacking arrangement of TCNQ dimers. It is a quasi-one-dimensional semiconductor up to 300 K with an energy gap Ec = 0.22 eV. The magnetic susceptibility follows quite well a Bonner-Fisher law with / = 76 K. At room temperature x = 9.5 x 10-4 emu/mol and there is a maximum = 14.5 x 10 4 emu/mol at Tm = 100 K. There is also a probable spin-Peierls transition at 5.5 K [64]. 

The salts of this series [BEDT-TTF = bis(ethylenedithiolo)tetrathiafulvalene], with X = AuBr2, CuCl2, or Ag(CN)2, are all semiconductors with narrow band widths and strong Coulomb repulsions. For this series the magnetic susceptibility has room-temperature values of = 8 to 9 x 10 4 emu/mol, and maximum values of = 16 to 18 x 10 4 emu/mol, at TM = 60 to 70 K. However, it does not fit well a Bonner-Fisher law in any case. A spin-Peierls transition is found to occur, at 7 K, for the Ag(CN)2 salt only [65]. 

The structure of this salt consists of stacks of twisted dimers. It is a semiconductor with an energy gap Ec = 0.42 eV. At room temperature the electrical conductivity is crM = 0.1 S/cm and the magnetic susceptibility is X = 8 x 10-4 emu/mol. As in the preceding a -(BEDT-TTF)2X series, the magnetic susceptibility does not fit well a Bonner-Fisher law [66]. 

Intense research has in recent years been devoted to noncrystalline materials. It was discovered also that the majority of semiconducting boron-rich borides display several properties that resemble those of the noncrystalline solids. Among the amorphous properties are the temperature and field dependencies of electrical conductivity at low temperature, the temperature dependence of thermal conductivity at high temperatures, and the temperature dependence of the magnetic susceptibility. In addition, the boron-rich semiconductors display crystalline properties, for example, the temperature dependence of the thermal condnctivity at low temperatures, the lattice absorption spectra and the possibility to change... 

---