Magnetic and electric properties are studied of an organic ferromagnet of pyrolysed polyacrylonitrile (PAN) and of its composites with an epoxy which are of great interest for practical use. Possible models of the pyro‐PAN ferromagnetic macromolecules are presented. Unusual magnetic properties of the composites obtained such as sign inversion of their magnetic susceptibility with increasing strength of the external magnetizing field are found. Dependences of their dielectric and magnetic constants on the electromagnetic wave frequency are obtained.

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P h y s i c s , Tashkent S t a t e U n i v e r s i t y , Tashkent 700095, U.S.S.R.A f t e r t h e first r e p o r t of t h e o r g a n i c ferromagnet' (poly-BIPO) q u i t e a number of works devoted t o a ferromagnetism i n o r g a n i c s u b s t a n c e s has appeared ( s e e t h e review a r t i~l e s~-~ ). A t p r e s e n t t h e i n t e n s i v e s e a r c h a r e b e i n g c a r r i e d on of new o r g a n i c ferromagnets w l t h t h e high s a t u r a t i o n magnetization. Here we first r e p o r t of o b t a i n i n g t h e new o r g a n i c f e r r omagnet by t h e p y r o l y s i s of a p o l y v l n y l c h l o r l d e (PVCH). A t e c hn i c a l gVCH (-C CHC1-), h a v i n g t h e molecular mass of about 1.2xIO '1188 U B~ f o r pyrOlgEi6 i n vacuo. The temperature i nc r e a s e was r e a l i z e d i n t h e d e s c r e t e s t e p s on IOOK H i t h t h e del a y of I h on each reached v a l u e . The o b t a i n e d product w a s crushed by t h e u l t r a s o n i c d i s p e r s e r i n t o a powder with t h e average g r a i n s i z e of about 80 Hm. The f e r r o m a g n e t i c phase f o r m a t i o n v e r s u s t h e WCH p y r o l y s i s temperature (Tp) was s t ud i e d by two independent methods such as t h e e l e c t r o n i c s p i n resonance (ESR) and t h e vibromagnetometer. A s s e e n from t h e t a b l e I t h e c o n c e n t r a t i o n of paramagnet i c c e n t e r s grows w i t h i n c r e a s i n g f@e p y r o l y s i s t e m p e r a t u r e and a c h i e v e s t h e m a x i m u m (n-4.5xIO spins/cm3) a t Tp=773K. The resonance a b s o r p t i o n l i n e s h a p e undergoes changes from t h e Gau s s i a n form t o t h e L o r e n t z i a n one and i t s h a l f -w i d t h i n c r e a s e s from 2.8 G a t T, =473K t o 8.5 G a t T, =873K. It t e s t i f i e s of t h e T a b l e I. Data of t h e ESR s p e c t r a s p i n c o n c e n t r a t i o n and t h e s a t ur a t i o n m a g n e t i z a t i o n I, f o r h C H pyrolysed a t d i f f e r e n t temperatures T,.