It might depend on context. Here is a line from the UCLA Visualization Portal:
By saying there is a knot here, we're suggesting that the relationship between x to y for x < 10 is different from the relationship for x > 10.
More than one announcer at a local, university-affiliated has started using the phrase "between x to y." This grates on my ear. I have always used "between x and y." Is the former grammatically correct?
"to" is probably used when talking about trajectories/trace-routes.
"The relation between x to y ..." is incorrect in standard English.
I can't think of a good context for "between x to y", unless x can stand for two things.
If x and y have numerical values, it might not refer to any kind of extent. 'Let the water boil for between 1 to 2 minutes.' (The 'between' is redundant there, but it still might be said)..
Phew! ('Things go better with COCA' as they say.)
Thanks to all. I should have given the actual example which has been in forecasting future temperatures, i.e. "tomorrow's temperature will be between 75 to 80 degrees."