E.i. Dupont De Nemours and Company

Ta Instruments, Inc.

Sanford M Marcus

Joseph R Rellick

Torence J Trout

Paul C Donohue

Lyla M El-Sayed

Michael Reading

A method and apparatus for measuring the thermal conductivity of materials using modulated differential scanning calorimetry (MDSC). Two MDSC heat capacity measurements are made consecutively. One measurement is made under conditions which ensure obtaining a fairly accurate value for the heat capacity of the material ('quasi-ideal conditions'). Another measurement is made under conditions such that the measured effective heat capacity differs from the accurate value of the heat capacity due to thermal conductivity effects. Generally, the non-ideal conditions differ from the ideal conditions by one parameter, such as the size of the sample, the modulation frequency used to measure the heat capacity, or, for thin films, the presence or absence of a specimen on the thin film. The thermal conductivity of the material is then calculated from the difference between the heat capacity measured under quasi-ideal conditions and the effective heat capacity measured under non-ideal conditions.

Method and apparatus for thermal conductivity measurements

Bipolar liquid electrostatic developer consisting essentially of at least one charge director in a nonpolar liquid having dispersed therein two toner particles having opposite charge polarity which comprise at least one thermoplastic copolymer resin. The particle average by area size is less than 10 .mu.m. The ratio of the two toner particles is 5 to 95 and 95 to 5. A process of simultaneous transfer of such developer is included. The developer is useful in copying.

Bipolar liquid electrostatic developer

An Al-Mg alloy is mixed with a Ni-Sb alloy or Al, in powder form, to form a thick-film metallizing paste useful for making low resistance electrically conductive contacts to a silicon solar cell coated with Si.sub.3 N.sub.4.

Silicon solar cells with aluminum-magnesium alloy low resistance contacts

The n-type region of a silicon solar cell is metallized with a nickel-antimony alloy to provide an external contact.

Silicon solar cell N-region metallizations comprising a nickel-antimony

Aluminum-magnesium alloys in low resistance contacts to silicon

A silicon solar cell is metallized with a nickel-antimony alloy to provide external contacts.

Solar cell metallizations comprising a nickel-antimony alloy

Temperature coefficient of resistance (TCR) modifiers, useful in thick film resistor compositions, which can be fired in nonoxidizing atmosphere and which are based on LaB.sub.6 and glass powders dispersed in a vehicle, are provided. Among such TCR modifiers are included TiO, Ge, Si, and graphite.

Temperature coefficient of resistance modifiers for thick film resistors

Conductive silver compositions useful for producing in a single application step solderable metal coatings on titanate bodies especially semiconducting ceramic titanate bodies, the silver compositions comprising specific amounts of finely divided silver; boron, Ni.sub.3 B, and/or certain nickel boride/phosphides; and a binder which is glass and/or PbF.sub.2. These inorganic solids are dispersed in an inert liquid vehicle. Also these compositions fired on a dielectric substrate.

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Wilmington, DE, United States of America

Sanford M Marcus