http://www.bretl.com/tvarticles/docu...HiLite0867.pdf
(3 MB pdf, 12 pages))
Brochure touting the features and quality of RCA color CRT's, published in August 1967.
Note the chart of CRT brightness improvements on p.4. Brochure says the latest is yttrium oxysulfide:europium, and is better than previous rare-earth screen, which I'm guessing was a vanadate rare earth red.
P. 6 illustrates the beam current ratios. This is still for the cyan-tinted 9300 degrees K +27 MPCD white color. The brochure claims this is less cyan than some TV makers had been using. If you plot this white point, it is obvious that the tube is still lacking red, only not anywhere as severely as earlier tubes.
This cyan white was one of the contributing reasons for poor color stability, as people would turn up the color to get pinker flesh tones, making the set more susceptible to signal variations. By the mid 70's, Zenith had moved to an 8000 K white, still not the studio standard, but much less blue. Some sets, like Mitsubishi CRT rear projectors, stayed very cyan to the end.