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High vacuum evaporation
VACUUM Classified Abstracts
III - -
Vacuum
30 ~
Processing
Techniques
EVAPORATION
--
--
III
3°
High V a c u u m Evaporation United States. E v a p o r a t i n g 2 m u t u a l l y miscible non-metallic materials from a c o m m o n crucible at reduced pressure, v a p o u r s are generated which contain the t w o materials in a ratio which is related to the ratio of the solids forming the original charge b y the phase diagram for the operational pressure. An analysis of the v a p o u r can easily be effected as the deposit obtained is of the same ratio as the v a p o u r phase. T h u s in a series of e x p e r i m e n t s it is possible to collect d a t a for the liquid-vapour phase diagram. The information is often needed in the deposition of anti-reflection coatings where the latter are required to have a refractive index inbetween the values of t h e refractive indices of the 2 pure components. The technique could also be applied in connection with e v a p o r a t i o n of 2 metallic materials, for instance for the production of metal-alloy mirrors. Sommaire: A~vis est donn~ sur la fagon de proc~der la ddposition des couches anti-rSfl~chissants sous vide Iorsque un indice de rdfraction intermddiaire entre ceux de deux c o m p o s a n t s pures est demand6 p o u r le dep6t.
O
O
Abstract No. and References
Metallising of Glass, Ceramic and Plastic Surfaces United K i n g d o m . Three basic m e t h o d s of depositing metal fihns on the surfaces of materials are discussed, i.e. reduction from a q u e o u s solutions, reduction b y heat, and v a c u u m evaporation. The deposition of silver films b y the first m e t h o d can be effected b y cane sugar reduction, formaldehyde-Rochelle salt reduction or b y hydrazine s u l p h a t e reduction. Details of the composition employed are given. The Rochelle salt reduction gives the best results so far as adhesion is concerned. The production of copper, gold and a n t i m o n y deposits b y this m e t h o d is described. The m e t h o d of reducing metal c o m p o u n d s b y heat is limited to materials which have a sufficiently high h e a t resistance on one band, and to metals, the c o m p o u n d s of which are reducible b y h e a t i n g on the other. Suitable materials are the salts of silver, gold, p l a t i n u m and palladium and suitable s u b s t r a t e s are ceramics. Details of the deposition of silver, gold and p l a t i n u m b y this m e t h o d are given. Finally the basic facts are given on the m e t h o d of depositing metal films by v a c u u m evaporation. The t h i n films produced b y a n y of the 3 m e t h o d s can be thickened b y m e a n s of electrodeposition. I n order to p r e v e n t chemical a t t a c k the t h i n films are first t r e a t e d in a special plating b a t h before t h e y are transferred to the n o r m a l b a t h . I n the case of silver films it is r e c o m m e n d e d t h a t the special b a t h consists of silver nitrate (25 g.), sodium cyanide (28 g.), p o t a s s i u m nitrate (100 g.), and w a t e r (1 litre.). The c u r r e n t density should be 0.5 A / s q . dm. Silver anodes should be used and the t e m p e r a t u r e of the b a t h should n o t be below 25°C. After the deposition of 0.0005 inch of silver the p a r t can be transferred to a b a t h of the n o r m a l composition. Similar r e c o m m e n d a tions are m a d e for the coating of copper and nickel b y electrodeposition. A typical application of the m e t h o d of reduction from a q u e o u s solutions is the deposition of silver on insulating materials to provide a conducting layer for uses in electro-forming practice. The firing m e t h o d is used for decorative p u r p o s e s on potter)- and lately also in the m a n u f a c t u r e of resistances. ,\pplications for the evaporation m e t h o d s h o w n are: Mirrors, selenium rectifiers and photocells. Sommaire : U n e x a m e n gdndral concernant t o u t e s les mdthodes connues de m6tallisation sur verre, cdramique, et surfaces de mati~re plastique.
]3d/III
Letter by J. E. Tyler J. Opt. 8oc. A met. 43, August 1952 7O8
137/III
Article by R. J. Heritage & .l.R. Balmer M etallurgia 47, April 1953 171-17l
The Effect of the Substrate Temperature on the Condensation Coefficient of Evaporated Antimony, Gold and Silver See A b s t r a c t No. : 221/I
138/III
On the Structure of Thin Silver Layers See A b s t r a c t No. : 220/I
139/III
Capacitance Effects in Thin Conductive Films United States. The frequency dependence of the electrical resistance of t h i n films of lead sulphide and tellurium w a s c o m p a r e d w i t h the frequency characteristics of models consisting of suitable resistance capacitance networks. The model corresponding to microcrystalline s t r u c t u r e was represented b y a n e t w o r k of intercrystallite resistance and capacitance and the internal resistances of crystallites while the model of a h o m o g e n e o u s resistor was represented b y a n e t w o r k of distributed resistances and capacitances. F o r m u l a e derived b y C h a s m a r of the equivalent parallel resistance capacitance n e t w o r k for the microcrystalline model and b y H o w e for the distributed model were used in this paper. The models were also interpreted for t e m p e r a t u r e dependence. I n the case of a model of p r e d o m i n a n t l y intercrystallite capacitance the t e m p e r a t u r e effect should be more marked. M e a s u r e m e n t s of the resistance versus frequency characteristics and its t e m p e r a t u r e dependence for 2 tellurium films and 1 lead sulphide film were c o m p a r e d w i t h the frequency characteristics of equivalent models. A tellurium film fitted the concept of distributive capacitance while the o t h e r films could best be fitted to a model based on a c o m b i n a t i o n of h o m o g e n e o u s and microcrystalline structure. B o t h t y p e s of film showed p h o t o c o n d u c t i v e properties. Sommaire : La relation entre la s t r u c t u r e du film et les effets capacitifs de couches de sulphure de p l o m b et de tellurium est dtudi6e.
140/III
October, 1953 VoL
Vacuum III No. d
Article by J. N. Humphrey, F. L. Lummis & W. W. Scanlon Phys. Rev. 9o, AI)ri| 1953 111-114
464
III - -
Vacuum
30 ~
Processing
Techniques
EVAPORATION
--
--
III
3°
High V a c u u m Evaporation United States. E v a p o r a t i n g 2 m u t u a l l y miscible non-metallic materials from a c o m m o n crucible at reduced pressure, v a p o u r s are generated which contain the t w o materials in a ratio which is related to the ratio of the solids forming the original charge b y the phase diagram for the operational pressure. An analysis of the v a p o u r can easily be effected as the deposit obtained is of the same ratio as the v a p o u r phase. T h u s in a series of e x p e r i m e n t s it is possible to collect d a t a for the liquid-vapour phase diagram. The information is often needed in the deposition of anti-reflection coatings where the latter are required to have a refractive index inbetween the values of t h e refractive indices of the 2 pure components. The technique could also be applied in connection with e v a p o r a t i o n of 2 metallic materials, for instance for the production of metal-alloy mirrors. Sommaire: A~vis est donn~ sur la fagon de proc~der la ddposition des couches anti-rSfl~chissants sous vide Iorsque un indice de rdfraction intermddiaire entre ceux de deux c o m p o s a n t s pures est demand6 p o u r le dep6t.
O
O
Abstract No. and References
Metallising of Glass, Ceramic and Plastic Surfaces United K i n g d o m . Three basic m e t h o d s of depositing metal fihns on the surfaces of materials are discussed, i.e. reduction from a q u e o u s solutions, reduction b y heat, and v a c u u m evaporation. The deposition of silver films b y the first m e t h o d can be effected b y cane sugar reduction, formaldehyde-Rochelle salt reduction or b y hydrazine s u l p h a t e reduction. Details of the composition employed are given. The Rochelle salt reduction gives the best results so far as adhesion is concerned. The production of copper, gold and a n t i m o n y deposits b y this m e t h o d is described. The m e t h o d of reducing metal c o m p o u n d s b y heat is limited to materials which have a sufficiently high h e a t resistance on one band, and to metals, the c o m p o u n d s of which are reducible b y h e a t i n g on the other. Suitable materials are the salts of silver, gold, p l a t i n u m and palladium and suitable s u b s t r a t e s are ceramics. Details of the deposition of silver, gold and p l a t i n u m b y this m e t h o d are given. Finally the basic facts are given on the m e t h o d of depositing metal films by v a c u u m evaporation. The t h i n films produced b y a n y of the 3 m e t h o d s can be thickened b y m e a n s of electrodeposition. I n order to p r e v e n t chemical a t t a c k the t h i n films are first t r e a t e d in a special plating b a t h before t h e y are transferred to the n o r m a l b a t h . I n the case of silver films it is r e c o m m e n d e d t h a t the special b a t h consists of silver nitrate (25 g.), sodium cyanide (28 g.), p o t a s s i u m nitrate (100 g.), and w a t e r (1 litre.). The c u r r e n t density should be 0.5 A / s q . dm. Silver anodes should be used and the t e m p e r a t u r e of the b a t h should n o t be below 25°C. After the deposition of 0.0005 inch of silver the p a r t can be transferred to a b a t h of the n o r m a l composition. Similar r e c o m m e n d a tions are m a d e for the coating of copper and nickel b y electrodeposition. A typical application of the m e t h o d of reduction from a q u e o u s solutions is the deposition of silver on insulating materials to provide a conducting layer for uses in electro-forming practice. The firing m e t h o d is used for decorative p u r p o s e s on potter)- and lately also in the m a n u f a c t u r e of resistances. ,\pplications for the evaporation m e t h o d s h o w n are: Mirrors, selenium rectifiers and photocells. Sommaire : U n e x a m e n gdndral concernant t o u t e s les mdthodes connues de m6tallisation sur verre, cdramique, et surfaces de mati~re plastique.
]3d/III
Letter by J. E. Tyler J. Opt. 8oc. A met. 43, August 1952 7O8
137/III
Article by R. J. Heritage & .l.R. Balmer M etallurgia 47, April 1953 171-17l
The Effect of the Substrate Temperature on the Condensation Coefficient of Evaporated Antimony, Gold and Silver See A b s t r a c t No. : 221/I
138/III
On the Structure of Thin Silver Layers See A b s t r a c t No. : 220/I
139/III
Capacitance Effects in Thin Conductive Films United States. The frequency dependence of the electrical resistance of t h i n films of lead sulphide and tellurium w a s c o m p a r e d w i t h the frequency characteristics of models consisting of suitable resistance capacitance networks. The model corresponding to microcrystalline s t r u c t u r e was represented b y a n e t w o r k of intercrystallite resistance and capacitance and the internal resistances of crystallites while the model of a h o m o g e n e o u s resistor was represented b y a n e t w o r k of distributed resistances and capacitances. F o r m u l a e derived b y C h a s m a r of the equivalent parallel resistance capacitance n e t w o r k for the microcrystalline model and b y H o w e for the distributed model were used in this paper. The models were also interpreted for t e m p e r a t u r e dependence. I n the case of a model of p r e d o m i n a n t l y intercrystallite capacitance the t e m p e r a t u r e effect should be more marked. M e a s u r e m e n t s of the resistance versus frequency characteristics and its t e m p e r a t u r e dependence for 2 tellurium films and 1 lead sulphide film were c o m p a r e d w i t h the frequency characteristics of equivalent models. A tellurium film fitted the concept of distributive capacitance while the o t h e r films could best be fitted to a model based on a c o m b i n a t i o n of h o m o g e n e o u s and microcrystalline structure. B o t h t y p e s of film showed p h o t o c o n d u c t i v e properties. Sommaire : La relation entre la s t r u c t u r e du film et les effets capacitifs de couches de sulphure de p l o m b et de tellurium est dtudi6e.
140/III
October, 1953 VoL
Vacuum III No. d
Article by J. N. Humphrey, F. L. Lummis & W. W. Scanlon Phys. Rev. 9o, AI)ri| 1953 111-114
464