U.S. Philips Corporation

Jonas Krober

Charlotte Jay

Olivier O Kahn

Renee Claude

Olivier O Khan

Francoise Groliere

Fran&ccedil;oise Groliere

Ren&eacute;e Claude

Francedillaoise Groliere

Methods and devices having means for writing storing and erasing which comprise an active medium containing at least one spin-transition parent compound

Spin-transition parent compounds

A chemical composition is provided for the manufacture of devices for storing and/or displaying information, comprising a network having a molecule which is formed from a metallic element Fe.sub.(II) which is bonded to a 1-2-4 triazole ligand (H-Trz), which molecule further comprises one or more than one anions A selected from BF.sub.4.sup.-, ClO.sub.4.sup.-, CO.sub.3.sup.2-, Br.sup.-, Cl.sup.-, in accordance with the formulation:

Spin-transition parent compounds and devices having means for writing,

Chemical substances are provided which exhibit thermally induced spin transitions between two stable spin states at ambient temperature, said transitions being associated with a hysteresis phenomenon and resulting in an abrupt variation of the color of the molecules for realizing a medium for storing, processing and/or displaying information by way of thermal writing, optical reading and thermal erasing, a particular embodiment of such a medium comprising at least a layer of chemical substances including a lattice with a molecule comprising a metallic element Fe.sub.(II), or Fe.sub.(III) or Co.sub.(II) associated with at least one ligand chosen from the substituted triazoles which are defined by the formula: ##STR1## in which R is H or an alkyl C.sub.n H.sub.2n+1 or R is an amine group NL.sub.2 where L is H and an alkyl radical, said molecule also comprising one or several anions chosen, for example, from BF.sub.4.sup.-, ClO.sub.4.sup.-, Br.sup.-, Cl.sup.-, and the lattice containing a defined quantity of non-ligand water, ensured by the presence of a hygroscopic substance.

Spin-transition compounds and their use for storing, processing and/or

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Paris, France

Jonas Krober